---
id: CVE-2026-88753
title: A Regular-Expression Denial of Service (ReDoS) in the Markdown2
summary: >-
  A Regular-Expression Denial of Service (ReDoS) in the Markdown2.
  extract_metadata() function (lib/markdown2.py) of trentm markdown2 through
  v2.5.5 allows attackers to cause a Denial of Service (DoS) via a crafted
  Markdown document.
severity: high
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T16:18:22.887'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88753'
references:
  - url: 'https://gist.github.com/NanaSec/354b4188bbd7f4105008c7b8be49b0ba'
    label: cve@mitre.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-88753.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-88753'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2553572'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-88753'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88753'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
  - score-dispute
ingestedAt: '2026-10-15T16:13:11.489Z'
epss: 0.0039
epssPercentile: 0.32967
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-20T02:31:53.253542Z'
cvssSource: adp
vendor: Red Hat
product: Red Hat OpenShift Container Platform 4
affected:
  - openshift_container_platform 4
cwe:
  - CWE-1333
scores:
  adp: 7.5
  vendor: 5.3
---

## Overview

A Regular-Expression Denial of Service (ReDoS) in the Markdown2. extract_metadata() function (lib/markdown2.py) of trentm markdown2 through v2.5.5 allows attackers to cause a Denial of Service (DoS) via a crafted Markdown document.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4 · updated 2026-10-20 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-88753.json)